Electric lamp.



L'Ae ORANGE.

ELECTRIC LAMP.

APPLICATION FILED SEPT. I

Patented Sept. 17,1918.

' In Vencor: v

a w 2 m m QM TZIAM s /H n he 0 ,J

I in a sealed envelop containing an indifferent JOHN A. ORANGE, 0F

soiimm'oran New YORK, assien'oar0 ems. comrm, A coaromrron or New YORK.

EnEc'mIc ELECTRIC LAMP.

To all 'wlwfn it may concern;

Be it known that I, JOHN A. ORANGE, a subject of the, King of Great Britain 're sidlng at Schenectady, county of certain new and useful Improvements in Electric Lamps, of which the following isja specification. A Q

The present-invention relates to electric lighting and comprises a lamp in which an arc is operated between electrodes of highly refractory metal, as, for example,'tungsten,

gas or vapor.

The eificiency of an incandescent filament lamp increases with the temperature of the incandescent filament. However, the rate of evaporation of a refractory metal when operated at lncandescence 1n a vacuum ncreases so rapldly wlth an increase of temperature that the operating temperature is limited to a value-at which the evaporation .will not be too rapid to give a useful length of life, and this is commonl a temperature corresponding to a light e ciency of about one watt per candle. An atmosphere of inert gas of relatively considerable pressure depresses the evaporation of a refractory metal, such as tungsten, to such extent that it has been found practicable to increase the operating temperature to a value at which a marked increase of vefficiency could be secured under certain conditions 1n spite of the heat losses due to gas convection currents, asdisclosed in Patent No. 1,246,118, granted to Dr. Irving Langmuir, on November 13, 1917: As the heat losses by convection are approximately independent of the diameter of the filament between certain limits and as the larger diameter filament with its greater surface area will radiate more light, it'has been found that the increased efliciency could be inost advanta geously obtained in lamps of large energy consumption. In lamps of small current the convection heat losses are greater in proportion to the light emission, due'to the decreased filament diameter, and in low I voltage lamps the heat losses by conduction from the terminals constitute a formidable proportion' of the energy losses. I It, therefore, has not been found practlcable to make incandescent lamps having a filament operating certain candlepowers.

ch enectady, State of New York, have invented in a gaseous atmosphere below Specification of Letters Patent. Patented Sept, 17, 1918. Application filed September 12, 1914. Serial No. 861,381. I I

A gaseous atmosphere of; relatively conreduce evaporation of the metal at a high temperature, as in the filament lamp above descrlbed, butv will also reduce the sput-' teringor electrical disintegration of the cathode due to an arc to such extent that a lamp of small candle power havin a commercially useful life may be made in which electrodes of tungsten, or equivalent refraca tory metal, are maintalned at lntensive 1n-.

candescence .by means of an arc. In this manner electrodes having the shape of hemispheres, cubes, disk or similar bodies of concentrated mass and small surface area may be heated to a temperature oflincandescence at which the efficiency of light production is about one-half watt per candle siderable pressure is efficacious not only to power or even greater, although these bodies could not be heated by heat developed due to their ohmic resistance alone Without pro- I hibitive loss of heat at the terminals.

The are in addition to its. function of heating its'electrodes may contribute a portion of the light at high efliciency provided the inert gas is so chosen that the arc is luminous, for example, as is the case in mercury vapor, but preferably the arc gap is 1 of the same order of magnitude as the electrodes, and hence usually the light from the arc represents only a small, fraction of the light emitted by the lamp.

Inorder that the lamps may be operated at thehigh temperature at which the-increased efliciencyof light production would more than off-set the cooling efiect of the gas, it is desirable that the current-carry- I ing conductors for the electrodes should be.

ing a gaseous atmosphere, the electrodes being so proportioned that the advantages of a aseous atmosphere at relatively con- 'sldera le pressure in an lncandescent lamp may be secured in lamps of very small rating. i p

Inthe accompanying drawings, Figure 1 illustrates my invention in a lamp employing aninert fixed gas, such as nitrogen or argon; Fig. 2 illustrates a lamp containing .are at incandescence, for

a body of mercury which during the operation of the device is vaporized at least in part, and surrounds the arcing electrodes; and Fig. 3 illustrates diagrammaticall the electrodes of a lamp adapted for irect current operation.

The lamp as shown in Fig. 1 comprises as usual a transparent glass or the like, provided in the usual manner with leading-in Wires 2, 2. sealed into a stem 4., and making connection to supporting conductors 3, 3 consisting of nickel or tungsten. To the conductors are secured the terminals 5, 6 which separate the arcing electrodes 7, 8. The terminal wir e s 5, 6 may be joined to the conductors3, 3 in' any convenient manner, as by sealing Or by merely mechanically pinching the ends of the wires 3, 3 around terminals 5, 6 while heated.

.The terminal Wires 5, 6 should be made as small in diameter as consistent with their function of carrying the operating current of the lamp so'as to reduce to a minimum the heat losses by conduction from the incandescent electrodes 7, 8. On the other hand the terminal wires 5, 6- should not be so small that they will operate at a high enou h temperature to become softened and de ormed.

refer-ably the terminal wires are reduced locally in section by etching or otherwise near the electrodes. F or, example, with electrodes of about 40 mils in diameter sep-- arated for a space of about 2 to 10 mils and designed tooperate with a current input of about .6 to .8 amperes, the wires may have a diameter of about .ZO-mils, etched down to a neck of about 1 to 8 mils. Both the electrodes and the terminals preferably consist of ductile tungsten, but my invention is equally applicable to electrodes of non-ductile metal and also to refractory metals other than tungsten, for example, tantalum.

The bulb 1 contains a gas having a relatively low heat conductivity and being inert in respect to the electrodes when the latter example, nitrogen, argon,-krypton, or other rare gases or mixtures of these may, be used. The pressure of the gas maybe varied and should preferably be so chosen that when it is heated to the operating temperature its pressure willapproximate that of the atmosphere, but pressures up to two atmospheres when operating can be used without much danger of the globe bursting. As a general rule the gas pressures may vary from about onefifth of an atmosphere upward and I have designated these pressures as relatively high,

e Geissler or Moore tube type. opera'tmg with an input of watts and a globe of about globe 1 consisting of.

' the electrodes.

rect current lamp lpressures heretofore employed,-

diameter, the gas pressure to 200 m. m. of mercury. The arc voltage varies with the character of the gas and the length of the gap but the voltage drop is in all cases relatively low. For example, in nitrogen at about atmospheric pressure the arc .voltage with a gap of about 2- to 4 mils is about 40 volts.

The lamp shown in Fig. 2 is similar to that already described in connection with: Fig. 1, but contains a quantity of mercury. The globe 9.may consist of low expansion borosilicate glass into which tungsten wires 10, 10 are sealed, but the character of the glass and the seal, of course, required by the operating temperature and other conditions. In this case the bulb contains a quantity of mercury 11 as well as an inert gas, such as nitrogen or argon, at a relatively considerable pressure, for example, about 150 to 250 m. of mercury, but in some cases the gas filling other than mercury may be omitted. In that casesome of may be chosen as the mercury preferably should be volatilized in the starting of the lamp. A lamp consuming about 50 watts may have a diameter of about 1-" at the arcing region constituted by the chamber 12 and a length of about 1%.

When as preferred a gas filling is provided in addition to the mercury, an arc is. first cury vapor displaces the lighter gas around ter the ar theelectrodes so that very soon-a displaced is started the nitrogen or argon is by the mercury vapor to the chamber 13 constituted by the upper part of the bulb.-

The are between theelectrodes 14, 15 operating in mercury vapor fillin th'e'chamber 12 is luminous and will contrlbute a part of light. I do not aim, however, to obtain any great proportion of the li ht from the arc, as my device is essential y an incandescent lamp heated by means of an arc, or, in other words; the energy consumed in the arc is substantially all utilized for heating In mercury vapor the arc voltage at about atmospheric pressure is about 10 to 20 volts with a current varying from 3.2 to .86 amperes.

The lamps shown in Figs. 1 and 2 have electrodes of substantially the same site and not are adapted particularly for alternating cur- I rent. s more heat is'liberated at the anode than at the cathode, the anode 17 in a diis preferably made larger than the cathode 16 as shown In Fig. 3.

What I claim" as new and desire to secure by Letters Patent of the United States, is

1. An electric lamp-comprising the combinatlOl'l of a sealed container, a gaseous filling therein having a, heat conductivity not substantially higher than nitrogen at a pressure greater than about 150 millimetersof mercury, tungsten "electrodes therein having a shape and mass adapting the same for incandescent-e in, said gas at a lighting eificiency materially higher than one watt per candle power, said electrodes being separated by a gap so short that the energy consumption of the arc is substantially all utilized for heating said electrodes. and refractory stems for said electrodes having a reduced section adjacent said electrode.

2. An electric lamp, COIIlPl'lSll'lg the combination of a sealed envelop, a filling of inert gas of low heat conductivity therein at a pressure approximating the pressure of the atmosphere at the operating temperature of the lamp, electrodes of tungsten having a diameter of substantially about one millimeter in said envelop separated from each other by a gap of the order of magnitude of about one millimeter, and refractory current-carrying conductors therefor, having' a section adjacent the electrodes reduced in diameter to conserve the heat generatedat said electrodes. ,7

An electric lamp comprising the combination of an envelop, tungsten electrodes of about the order of magnitude of about one millimeter, separated from each other by a gap of about the same order of magnitude as said electrodes, a filling of gas of low. heat conductivity and indifierent with respect to .said; electrodes at a pressure approaching one atmosphere when at the operating" temperature, termmal conductors having a section adjacent the electrodes 're- I duced m diameter and substantially large to heat said electrodes to incandescence.

4. An arc device comprising the combination of a sealed container, electrodes of refractory material therein proportioned to be operable at incandescence, current carrying conductors therefor having a section adjacent said electrodes reduced in diameter and a gaseous filling in said container-having a heat conductivity not materially higher than nitrogen at a pressure sufliciently high to substanti 11y suppress electrical disintegration of said electrodes during the operation of an arc therebetween. V

5. An electric lamp vcomprising the combination of an envelop, a filling of inert gas, such as argon, therein, at a pressure of about 150 to "200 mm. of mercury, tungsten elec-- trodes having a diameter of about-l=0 mils separated by a space of about 2 to 10 mils and proportioned to be heated to incandescence by an are operating between said ele'ctrodes, and current'carrying conductors for said electrodes having a diameter of-about '20 mils said conductors having a section adjacent the electrodes having; a diameter of about 4 to 8 mils.

In witness whereof I have hereunto set my hand this 8th day of September, 1914.

JOHN A. ORANGE.

Witnesses:

' HELEN Oaronn,

- BENJ. H. WEISBROD. 

